Proton beam

  • 8.89 GeV/c protons from the Fermilab Booster are incident on a beryllium target. The beam is modeled with measured mean position and angle with Gaussian smearing. MiniBooNE simulates the effects of varying the spread in the beam and different focus points of the beam.
  • The typical proton beam contains 4 x 10¹² protons delivered in a spill approximately 1.6 µs in duration.
  • The absolute number of protons on target (p.o.t) is measured by two toroids upstream of the target. The toroids track each other well, and toroid drift is the main contributor to the error in the number of protons. The error on the delivered p.o.t prior to March 2003 was 3%, and 1.7% since then.


  • The target measures 71 cm long, 1 cm in diameter, and is made out of seven 'slugs' of beryllium; it is 1.7 interaction lengths long, and its shape and cooling fins are modeled.


  • Magnetic focusing horn is pulsed at 174 ± 1 kA. The horn current pulse is a half sinusoid with half period of approximately 140 µs, with the peak current coinciding with the beam spill. Pulse timing is stable over time. We model 'skin depth', or penetration of the magnetic field into the surface of the conductor.


  • Produced mesons decay in 50 m decay region filled with air.
  • The geometry of whole beamline/target system has been verified by survey and other direct measures of the distance. Any change in the flux that could possibly arise due to geometry variations would have to come from variations detectable at this scale.